1. Field of the Invention:
The present invention relates to a method of making a tape-carrier for manufacturing IC elements, the tape-carrier comprising a flexible tape of an insulation material and a metal foil adhering to the tape. The present invention relates more particularly to a method of making a tape-carrier which is provided with a metallic bump on the end portion of each lead terminal in order to bond an IC chip easily with the lead terminals of the tape-carrier.
2. Description of the Prior Art:
One of the conventional methods for connecting each terminal of an IC chip with a corresponding lead terminal of a lead frame is to connect them discretely with a wire. However, such method takes much time and labor.
Another method is to use a tape-carrier which comprises a flexible tape of an insulation material and a metallic foil adhering to one surface of the tape. The metallic foil is etched or punched to have a plurality of lead terminals. The tape has a row of sprocket holes along each side edge thereof for positioning the tape-carrier accurately into a bonding station where an IC chip is bonded onto the lead terminals. After bonding, the tape-carrier is fed to another processing station by a sprocket wheel which engages with the sprocket hole. In this method, the IC chip is positioned on the lead terminals through a center hole of the tape. Thereafter, all of the terminals of the IC chip are bonded simultaneously to the lead terminals by a thermo-compression gang-bonding means. The IC chip used in the above-mentioned method heretofore is provided with terminal bumps each of which is placed on a corresponding lead terminal during the gang-bonding process. However, forming such terminal bumps on the IC chip makes it complicated to manufature the IC chip, thus causing an increase in the percentage of defective IC chip products and an increase in the cost of producing the IC chip.
The size of the average lead terminal is about 100 .mu.m in width and about 35 .mu.m in thickness. It is difficult to form a bump on the end of such a small lead terminal in a prescribed position with a high degree of accuracy after the lead terminals are constructed.
A bump can be formed on the end of each lead terminal of a lead frame by using a known IC element manufacturing process in which the above-mentioned tape-carrier is not used. This known process is disclosed in Japanese Patent Publication Sho. No. 45-40740. However, the conventional process is complicated because the lead frame comprises many layers of various metals, each layer being treated by an etching process. Therefore, the possibility of mis-alignment of each layer is increased.